OREANDA-NEWS. The liquidity of economic bids for exports and imports into California's primary grid remains low a year after the 15-minute cycle for scheduling capacity and price settlement was introduced at interties — and the grid operator does not have an explanation for the trend.

The California Independent System Operator switched to 15-minute scheduling in May 2014, even though neighboring balancing areas have not kept up with the transition. The transition from hourly to 15-minute scheduling stems from the Federal Energy Regulatory Commission's mandate known as Order 764, which aims to integrate renewable and other variable energy resources whose output varies quickly.

Few economic bids for exports or imports occur in the 15-minute cycle at most California interties even though the market has had almost a year to adjust to the new scheduling cycle, according to the grid operator's department of market monitoring.

The grid operator told federal energy regulators it "does not yet understand the causes of this low market liquidity." Possible causes include difficulty in procuring transmission in 15-minute blocks, lack of bilateral trading in 15-minute cycle and the "reticence of resource owners to adjust their output within the hour."

Several market participants, including power importers, said that real-time prices began to move too unpredictably for imports into California after the change, so trading volumes moved into the day-ahead market or were replaced with self-scheduling for fixed hourly blocks. A self-schedule is a bid or offer for electricity that agrees to accept whatever price is set in the market.

The low liquidity will deter the grid operator's plans to re-introduce convergence bidding at interties in May. The operator has asked the Federal Energy Regulatory Commission to delay the start of virtual bidding until May 2016, citing lack of economic export and import bids in the 15-minute cycle.

Convergence — or virtual — bidding enables electricity traders to make purely financial sales or purchases of electricity in the day-ahead market with the explicit requirement that they undertake the opposite transaction in the real-time market.

In theory, convergence bidding pressures big power purchasers not to under-schedule demand in the day-ahead market with the hopes of getting lower real-time prices, thereby converging prices between the two markets. But California's experience with convergence bidding in 2011-12 showed that that market mechanism did not work as planned, so the grid operator suspended such trading and planned to reintroduce it next month.

Reintroducing convergence bidding under current market conditions will allow market participants to make a guaranteed profit from differences in congestion prices in the day-ahead market and the highly illiquid real-time 15-minute market, the grid operator said.