Distribution grid operators are concerned that high penetration of connected distributed energy resources (DERs) could lead to grid instability and create outages at end-user sites, such as commercial buildings or industrial plants. \u201cToday, we don\u2019t fully understand grid behavior under varying DER conditions, and are not sure how to address this properly,\u201d said Fred Oshiro, Engineer from Maui Electric in Hawaii, during a DistrbuTECH panel discussion on January 2018.<\/p>\n\n\n\n
Indeed, industrial consumers such as\nfactories, labs with expensive equipment, and tool fabrication shops can also\nbe impacted by unexplained malfunctions, resets, and shutdowns \u2014 all without\nany apparent power-related causes. Power supply units overheat and occasionally\ncatch fire without circuit breakers ever tripping. Additional problems have\nbeen observed with street lighting control, interruptions in Power Line\nCommunication (PLC), and even incorrect energy meter readings.<\/p>\n\n\n\n
Power quality issues can stem from\ngrid-connected power inverters, which are widely used in renewable generation\nto convert DC to AC and then connect solar PV, wind farms or batteries to the\ndistribution grid. Inverters are designed and tested for compatibility\nindividually, but the behavior of the control loops of multiple inverters\nconnected as a system is unknown.<\/p>\n\n\n\n
Inverters, as well as frequency converters\nand variable frequency drives (VFDs), are high-frequency switching devices,\ntypically from 2 kHz to 200 kHz. Those devices can leak high-frequency\nconducted emissions into neighboring buildings and factories via the grid. As a\nresult, commercial buildings and facilities located near renewable generation\ncan be affected, though not necessarily in a predictable way. The intensity\nlevels of emissions vary with distance from the source, inverter manufacturer\ndesign, and the presence of other inverters in the neighborhood.<\/p>\n\n\n\n
Is this problem insurmountable? How can we\nefficiently troubleshoot issues that occur intermittently on the factory floor\nor in sensitive manufacturing areas, like semiconductor fabs or data centers?<\/p>\n\n\n\n
As Lord Kelvin once said, \u201cIf you cannot\nmeasure it, you cannot improve it,\u201d and this applies perfectly in this\nsituation. The art of field troubleshooting consists of systematically closing\ndoors to hypotheses to narrow down to the most probable cause (or root cause).\nTo validate a hypothesis, you need to have measurements and the ability to\nprecisely detect all disturbances, not just the most common ones.<\/p>\n\n\n\n
The most common disturbances are voltage\nvariations (rapid variations or sags, swells, interruptions), high levels of\nharmonics, system imbalance, high-frequency impulses, and in-rush currents.<\/p>\n\n\n\n
Until recently, high-frequency conducted\nemissions in the 2-150 kHz range could remain under the radar of power quality\ninvestigations, due to lack of field measurement tools and data. Advancements\nin technology have led to new generations of ultra-precise instruments that\ncontinuously monitor the quality of AC and DC power, and detect and record all\ntypes of disturbances overtime at an affordable cost.<\/p>\n\n\n\n
The image above shows a measurement graph\nautomatically generated using an ultra-precise power analyzer. This is a\ntime-based color map of high-frequency conducted emissions across a full day.\nIntermittent emissions at 130 kHz can be clearly identified. In this\ntroubleshooting example, the periods of emissions activity coincided with\nobserved failures on the shop floor of a factory. The minute granularity of the\ncolor map enabled the factory operator to conclusively confirm a strong\ncorrelation between those specific emissions and the equipment failures. Once\nthe source was identified, the power maintenance engineer selected and\ninstalled a specific filter to protect the sensitive equipment. The equipment\nhas since been operating reliably, without any issues.<\/p>\n\n\n\n
The mitigation of high-frequency emissions\nmust be coupled with the development of industry standards that will provide\nguidance for both grid operators (compatibility) and equipment manufacturers\n(immunity).<\/p>\n\n\n\n
The IEC standard 61000-2-2 Ed. 2 AMD1\nprovides some guidance on limits in the range 2-30 kHz. IEC 61000-4-19 provides\nguidance on immunity levels for equipment connected to an electrical network.\nBut there is, unfortunately, no real guidance as yet on emissions levels and\ntheir severity within factories (i.e., behind-the-meter locations)<\/p>\n\n\n\n
In June 2017, California generated 27\npercent of its electricity from renewable sources, on its way to a mandated 50\npercent renewables by 2030. Maui Electric Company currently receives more than\n37 percent of its energy from renewables, with a statewide goal of 100 percent\nrenewables by 2050. In fact, more than 35 other states have renewable portfolio standards<\/a> calling for greater use\nof clean energy sources.<\/p>\n\n\n\n As DER penetration increases, especially in\nislander grids and microgrids, power quality and the methods that we use to\ndetect and analyze it will need to remain top of mind for energy users.<\/p>\n\n\n\n Stephane\nDo has 20 years of experience in the power quality business and is a\nglobal Product Manager at Powerside formerly Power Standards Lab.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":" Understanding the Unintended Consequences of Renewable Energy Distribution grid operators are concerned that high penetration of connected distributed energy resources (DERs) could lead to grid instability and create outages at end-user sites, such as commercial buildings or industrial plants. \u201cToday, we don\u2019t fully understand grid behavior under varying DER conditions, and are not sure how … DER Disruption<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":12242,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[113],"tags":[],"class_list":["post-283","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-utilities-der-microgrid"],"acf":[],"_links":{"self":[{"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/posts\/283","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/comments?post=283"}],"version-history":[{"count":1,"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/posts\/283\/revisions"}],"predecessor-version":[{"id":14991,"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/posts\/283\/revisions\/14991"}],"wp:attachment":[{"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/media?parent=283"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/categories?post=283"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/wp-json\/wp\/v2\/tags?post=283"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}